1. Field of the Invention
This invention relates to small internal combustion engines of the type commonly used in lawn mowers, lawn and garden tractors, snow throwers, other working implements, or in sport vehicles. In particular, the present invention relates to heating the intake air and the carburetors of such engines.
2. Description of the Related Art
Small internal combustion engines typically include a carburetor which mixes ambient atmospheric air with liquid fuel to provide an air/fuel mixture for combustion within the engine. Usually, the intake air is drawn from the atmosphere through an air filter to remove dirt and other debris from the intake air before the intake air enters the carburetor. A potential problem in such arrangements is that when the engine is used in a cold environment, such as in a snow thrower application, the intake air is often cold and moist, and may include snow. The moisture in the cold intake air may freeze and accumulate within the carburetor, causing the carburetor to “freeze up” and inhibit good engine performance.
It is known to provide small single cylinder engines with duct arrangements which are disposed near the engine muffler. In operation, the duct is heated by radiant heat from the muffler during running of the engine. Air is drawn through the duct by the carburetor, and the air is heated before it enters the carburetor. However, such ducts are typically formed from two or more separate components which fit together and cooperate to define the duct, and therefore, multiple parts are required.
A further problem in many small engines is that the carburetor itself is often positioned in a manner in which it is exposed to the cold environment, potentially leading to carburetor “freeze up”. For example, the carburetor may be positioned on one side of the engine in such a manner that at least a portion of the body of the carburetor is disposed externally of the engine enclosure structure and is exposed to the environment.
What is needed is an intake air and/or carburetor heating arrangement for small internal combustion engines which is an improvement over the foregoing.
Also, intake air and/or carburetor heating arrangements which are adapted for use with V-twin engines are not known, thus, a further need is for an intake air and/or carburetor heating arrangement for a V-twin engine.